Drivers of the Benefits, Costs, and Trade-offs of Spatial Management

ICES ASC 2023 – Bilbao, Spain

Dan Ovando – Inter-American Tropical Tuna Commission

Trade-offs of Spatial Management?

  • Growing focus on spatial management (BBNJ,30x30)

  • Trade-offs are critical area of research

    • More protection \(\approx\) more conservation

    • At what cost?

  • Science of MPA outcomes largely based on simulations 1

  • Quality of advice depends then on simulations being reasonably realistic

Model Structure Matters

Ovando et al. 2023 reply to Sala et al 2020

1) How variable are MPA outcomes?
2) What social-ecological traits drive results?

The marlin Model

https://danovando.github.io/marlin/

The marlin Model

Simultaneously simulate…

Fish

  • N age-structured populations

  • Larval & adult dispersal governed by habitat gradients (CTMC)

  • Lots of life history bells & whistles

Fleets

  • N fleets targeting one or more of simulated species

  • Species-specific selectivity, price, etc.

  • Allocate in space and time based on range of possible economic and regulatory factors

Simulating Outcomes of Spatial Management

Given three species and one fleet, randomly draw…

  • fishing mortality

  • adult and larval movement rates and density dependence timing

  • lots of other economic and environmental attributes

Then apply no-take MPAs…

  • Of different sizes

  • With different design strategies

MPA Outcomes are Highly Variable

Many Social-Ecological Traits Matter

What About Climate?

We Need To Put Models To The Test

  • Policies have complex effects in social-ecological systems, particularly the less direct they are

  • Overly simple models can produce unreliable projections of conservation and food security outcomes

  • Models that reasonably capture complexity and dynamism of open oceans needed to make objectives like BBNJ effective

  • Next generation of MPA science needs to confront models with data

Questions?

Distributional Trade-Offs Matter

Distributional Trade-Offs Matter